Synthesis and characterization of 2-(2-benzhydrylnaphthyliminomethyl)pyridylnickel halides: formation of branched polyethylene

A series of 2-(2-benzhydrylnaphthyliminomethyl)pyridine derivatives (L1–L3) was prepared and used to synthesize the corresponding bis-ligated nickel(II) halide complexes (Ni1–Ni6) in good yield. The molecular structures of representative complexes, namely the bromide Ni3 and the chloride complex Ni6, were confirmed by single crystal X-ray diffraction, and revealed a distorted octahedral geometry at nickel. Upon activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all nickel complex pre-catalysts exhibited high activities (up to 2.02 × 10⁷ g(PE) mol⁻¹(Ni) h⁻¹) towards ethylene polymerization, producing branched polyethylene of low molecular weight and narrow polydispersity. The influence of the reaction parameters and the nature of the ligands on the catalytic behavior of the title nickel complexes were investigated

Searching for Charged Higgs Boson in Polarized Top Quark

The charged Higgs boson is quite common in many new physics models. In this study we examine the potential of observing a heavy charged Higgs boson in its decay mode of top-quark and bottom-quark in the Type-II Two-Higgs-Doublet-Model. In this model, the chirality structure of the coupling of charged Higgs boson to the top- and bottom-quark is very sensitive to the value of $\tan\beta$. As the polarization of the top-quark can be measured experimentally from the top-quark decay products, one could make use of the top-quark polarization to determine the value of $\tan\beta$. We preform a detailed analysis of measuring top-quark polarization in the production channels $gb\to tH^-$ and $g\bar{b}\to \bar{t}H^+$. We calculate the helicity amplitudes of the charged Higgs boson production and decay.Our calculation shows that the top-quark from the charged Higgs boson decay provides a good probe for measuring $\tan\beta$, especially for the intermediate $\tan\beta$ region. On the contrary, the top-quark produced in association with the charged Higgs boson cannot be used to measure $\tan\beta$ because its polarization is highly contaminated by the $t$-channel kinematics.Comment: 21 pages, 12 figures, 2 table

Far-Field Tunable Nano-focusing Based on Metallic Slits Surrounded with Nonlinear-Variant Widths and Linear-Variant Depths of Circular Dielectric Grating

In this work, we design a new tunable nanofocusing lens by the linear-variant depths and nonlinear-variant widths of circular grating for far field practical applications. The constructively interference of cylindrical surface plasmon launched by the subwavelength metallic structure can form a subdiffraction-limited focus, and the focal length of the this structures can be adjusted if the each groove depth and width of circular grating are arranged in traced profile. According to the numerical calculation, the range of focusing points shift is much more than other plasmonic lens, and the relative phase of emitting light scattered by surface plasmon coupling circular grating can be modulated by the nonlinear-variant width and linear-variant depth. The simulation result indicates that the different relative phase of emitting light lead to variant focal length. We firstly show a unique phenomenon for the linear-variant depths and nonlinear-variant widths of circular grating that the positive change and negative change of the depths and widths of grooves can result in different of variation trend between relative phases and focal lengths. These results paved the road for utilizing the plasmonic lens in high-density optical storage, nanolithography, superresolution optical microscopic imaging, optical trapping, and sensing.Comment: 14pages,9figure

Theoretical insight into the structure and stability of TNT and RDX in external electric field

A comparison of the effect of external electric field on the C–NO2 or N–NO2 bonds with the C–H and N–O bonds in 2,4, 6-trinitrotoluene (TNT)or hexahydro-1,3,5-trinitro-s-triazine (RDX) has been carried out using the M06-2x method with the 6-311++G** and aug-cc-pVTZ basis sets. The result shows that for TNT the fields have a minor effect on the C–NO2 and C–H bonds but a major effect on the N–O bonds, while in RDX the fields greatly affect the N–NO2 bond but the N–O and C–H bonds are slightly affected. Thus, in TNT the N–O bond can be the trigger bond, and in RDX the N–NO2 bond is always the trigger bond in electric fields. The explosive sensitivities may be reduced and the stabilities may be increased under the external electric fields in the negative direction along the C–NO2 bond axis for TNT and in the positive direction along the N–NO2 or N–O bond axis for RDX. The opposite trends can be suggested in the fields of the opposite directions along above bond axes. The introduction of external electric field into energetic material may be an available way to adjust explosive sensitivity. The analyses of AIM (atoms in molecules) and frequencies support the above viewpoints. The linear correlations between the field strengths and the changes of N−O/N−N bond lengths, ρ(N−O/N−N) values, or stretching frequencies of the N−O/N−N bonds have been found